The present invention relates to a method of producing a fiber-reinforced composite material and specifically to a method of producing a unidirectional fiber-reinforced composite material.
In comparison with a non-directionally fiber-reinforced composite material, a unidirectionally fiber-reinforced composite material has by far excellent reinforcing effect and various attempts have therefore been made conventionally to improve its physical properties and its producibility. However, handling and arrangement of the fiber has been difficult. In order to improve this problem, there has so far been made a variety of proposals. For example, a method of directly arranging the fiber in a mold; a method of prearranging the fiber bundles by use of jigs, etc., placing the fiber bundles into a mold as they are and rendering them composite; a method of laminating or metallizing or vaporizing the fiber into a foil-like matrix in advance; a method of handling the fiber as a prepleg by means of organic or inorganic binders; a method that uses filament winding; and so forth. Most of them however are yet at the stage of research and fail to provide a really satisfactory solution.
The inventors of the present invention proposed previously a method of fiber-reinforcing a metallic member to be reinforced by forming, from an inorganic fiber, a fiber shaped body having an optional shape and bulk density and squeeze casting the shaped body into desired positions of the metallic member, and also various application techniques of said method. Unlike the conventional methods this method enables one to fill and combine the fiber body in and with the metallic member simultaneously with shaping of the metallic member itself. In other words, in accordance with this method the fiber shaped body is filled in and combined with a molten metal in an extremely efficient manner under a hydrostatically high pressure and thereafter cooled rapidly to solidify to thereby prevent damages of the fiber. At the same time the matrix can be reinforced markedly by squeeze solidification. Thus, the method made a great contribution to the practical use of the fiber-reinforced member by enabling the effective reinforcement of the member to be reinforced in consideration of its shape and function and the efficient utilization of the fiber.
The present invention further improves the above-mentioned production method of a fiber-reinforced composite material and is directed to provide a production method of a unidirectionally fiber-reinforced composite material which insures extremely easy and simple handling and shaping of the fiber body and which has a high production efficiency.
During the production process of the above-mentioned fiber-reinforced composite material, the inventors of the present invention examined a method of unidirectionally fiber-reinforcing a member to be reinforced and a method of arranging the fiber in view of the shape, function and stress-sharing of the member to be reinforced. Results of the examination will be explained with reference to the example wherein a connecting rod of an internal combustion engine (shown in FIGS. 1 and 2) is fiber-reinforced in a specific direction.
An aluminum alloy is used as the matrix metal and a stainless fiber of a 25.mu. diameter is shaped into the following three kinds of fiber bodies as the reinforcing fiber. As a result of the stress analysis of the connecting rod, it is found that the stress sharing is great at both end portions of the rod section, at the rib and the annular section at the small end. Hence, these portions are preferentially reinforced.
The specification of the reinforcing fibers are as follows.